The proliferation of portable (particularly handheld) electronic devices, especially those designed for RF communications such as mobile telephones, smartphones and tablets, has led to increased demand for cases to cover such devices. The case is normally designed to provide protection, particularly against dirt, water and other contaminants. Moreover, improved cases can provide protection to mitigate impact damage to the device, for instance when the device is dropped.
Such portable RF communications devices require an RF antenna arrangement (which may comprise one or multiple antennas). The antenna or antennas may be provided for cellular radio communication, wireless Local Area Network (LAN) communication, short-range networking and in cases, one antenna may be used for multiple types of communication. Early devices provided the RF antenna arrangement external to the device housing, for example as a whip antenna. Cases for such devices would not cover the antenna.
More recent devices have provided the RF antenna arrangement within the device or integrated with the device housing. For example, an RF antenna may be integrated with the device housing by being provided in the form of a conductive strip on an outer side of the housing. Typically, this strip is covered with an insulating material, such as a plastic coating, to mitigate any deterioration in RF antenna performance due to user or atmospheric contact with the antenna. Such antennas allow more interaction between the RF antenna arrangement and an additional case covering the device. Optimizing the interaction between the case and all components of the device, including the RF antenna arrangement, is a challenge for the case designer.